Browsing by Subject "Satiety"
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Item Changes in gastrointestinal hormones, leptin, and satiety after gastric bypass surgery(2012-06) Beckman, Lauren MarieThe Roux-en-Y gastric bypass (RYGB) is a well-accepted tool for the treatment of obesity and compared to conventional weight loss methods (e.g. diet and exercise) and other weight loss surgeries (e.g. gastric banding), it results in considerable weight loss that is maintained long-term. Although successful, the mechanisms for weight loss are not completely understood and it is thought that favorable changes in several gastrointestinal (GI) hormones and satiety play a role. Previous research suggests that the satiety promoting hormones, GLP-1 and PYY increase after RYGB, while the orexigenic GI hormone ghrelin and the adipocytokine leptin decrease. These changes generally occur before substantial weight loss, suggesting that a component of the surgery is responsible. Subjective satiety has also been reported to increase after RYGB, likely because of changes in the GI hormones and due to the reduced stomach capacity after surgery, but it is not clear if this alteration is maintained long-term. In addition, it is currently not well understood what effect different macronutrients have on the GI hormones and subjective satiety in the post-RYGB patient population. From a clinical perspective, there is a need for understanding how various macronutrients affect these parameters, as this is useful information that might allow for improved dietary treatment recommendations after RYGB. In the first study, changes in the GI hormones and leptin were evaluated after RYGB. This study also assessed if the GI hormones differed after a short-term dose of protein (PRO-BEV) or fat (FAT-BEV). GLP-1, PYY, ghrelin, and leptin were assessed in 16 women before and at 2, 6, 26, and 52 weeks after RYGB. GLP-1 increased at Weeks 6 and 52 in the FAT-BEV group compared to before surgery. PYY remained elevated at Week 52 in the FAT-BEV group. Ghrelin decreased at Weeks 2, 6, and 52 in the PRO-BEV group compared with Pre-RYGB. Ghrelin was lower in the PRO-BEV group compared with the FAT-BEV group at Week 6. Fasted leptin decreased at all visits in both groups and was lower in the FAT-BEV compared with the PRO-BEV group at Week 52. In the second study, subjective satiety was evaluated before and after RYGB. This study also assessed if subjective satiety differed after a dose of either protein or fat and investigated if subjective satiety, the GI hormones, and/or weight loss are related. Subjective satiety was not different between treatment groups. Satiety increased at the Week 2 visit compared to before surgery. Satiety scores had generally returned to Pre-RYGB levels after the Week 6 visit. Subjective satiety was not related to any of the GI hormones. Weight loss was unrelated to subjective satiety and the GI hormones. Results from these studies indicate that favorable changes occur after RYGB for the GI hormones/leptin and subjective satiety; some differences were evident soon after surgery (ghrelin, leptin, subjective satiety) while others were maintained long-term (GLP-1, PYY, ghrelin, leptin). In response to a short-term stimulus, protein suppressed ghrelin and fat stimulated GLP-1 and PYY. Although we did not find a difference in subjective satiety between beverage groups, assessment of the macronutrient effect on satiety is a novel analysis in this patient population, and further work is needed to better define the post-RYGB nutrition recommendations. Continued research in this area that attempts to better understand dietary components that could ultimately lead to successful weight loss/maintenance is needed for proper nutrition care after RYGB.Item Effects of fiber on satiety, food intake, glucose, insulin, and gut hormones in healthy human subjects.(2009-05) Willis, Holly JoEpidemiologic studies suggest that people who eat more fiber have a lower body weight than people who eat less fiber. Potential mechanisms for this relationship may include greater feelings of satiety, reductions in food intake, or changes in blood glucose, insulin, or gut hormone levels. The following work describes two unique intervention studies designed to help explain this relationship. In the first study we hypothesized that certain types of fiber would enhance satiety more than others when consumed in muffins for breakfast. Healthy men and women participated in this randomized double-blind, crossover study comparing satiety after subjects consumed four different fibers and a low-fiber control. Subjects used 100 mm visual analog scales (VAS) to rate satiety for 3 hours after muffin consumption. Satiety differed among treatments. Resistant starch and corn bran had the most impact on satiety, while polydextrose had little effect and behaved like the low-fiber treatment. In the second study we hypothesized that increasing doses of fiber would increase satiety and decrease food intake in a dose-dependent manner. We also hypothesized that glucose, insulin, ghrelin, GLP-1, and PYY3-36 would change in proportion to fiber dose. Healthy men and women participated in this randomized double-blind, crossover study. Subjects consumed muffins with 0, 4, 8, and 12 g of mixed fibers and proceeded to rate satiety with VAS over a three-hour period. Blood was drawn at regular intervals and ad libitum food intake was assessed at two different time points. The 12 g fiber muffin was consistently and significantly more satiating than the 0 g muffin; however, food intake did not differ among treatments. Glucose, insulin, ghrelin, and GLP-1 differed among treatment doses, but not in the manner we expected. Glucose and insulin did not correlate with each other or with appetite. Ghrelin was significantly higher after 12 g of fiber than after all other doses, and GLP-1 decreased consistently with fiber dose. PYY3- 36 did not differ among treatments. Results from these studies indicate that certain types and doses of fiber positively influence satiety. However, caution should be used when making blanket statements about fiber as a generic substance; this research suggests that some types and doses are not as effective as others. Furthermore, feelings of satiety may not be consistently linked to food intake or other commonly accepted physiologic measures for satiety.Item The effects of polydextrose and soluble corn fiber on laxation and satiety in healthy human subjects(2012-09) Timm, Derek AllenDietary fiber from whole foods has long been known to regulate bowel function; however it is essential to confirm this in isolated or synthesized fibers. Stool weight, gastrointestinal transit time, and stool consistency are all ways to measure changes in bowel function in humans and can be used to evaluate the efficacy of dietary fibers. Gastrointestinal tolerance is also of great concern since consumer acceptability of dietary fiber is related to intolerance issues. Furthermore, since observational and epidemiological data suggests dietary fiber reduces energy intake, which may be modulated by changes in postprandial satiety, we also investigated acute satiety using visual analog scale (VAS) and food intake via food diaries. Therefore, we investigated the influence of 20 grams per day for 10 days of the functional fibers Polydextrose (PDX) and Soluble Corn Fiber (SCF) compared a low fiber control on bowel function. Thirty-six healthy men and women completed this randomized, double-blind, placebo-controlled study. A two-week washout period was completed between each treatment period. Results show both PDX and SCF significantly increased stool weight compared to the control treatment. In contrast, whole gut transit time was not difference among the treatments. Stool pH was significantly lower for PDX compared to the control treatment. PDX caused a significantly looser stool than SCF and control. Flatulence and stomach noises were significantly increased by the fiber treatments compared to the control. Satiety was not difference among the treatments as measured by a VAS. No differences were observed in energy intake among the treatments.Item Effects of the combination of protein and fiber in whole foods on satiety, blood glucose response and food intake in humans(2014-06) Bonnema, AngelaThe obesity epidemic continues worldwide and is considered a major health concern. A shift back to consumption of whole foods may be an important part of the solution in the current rising obesity trend. Both protein and fiber have satiating properties, but few studies have examined whether their impact on different biological mechanisms work additively to more strongly enhance the overall satiety potential of a meal. In the first study, the objective was to determine the effects of a high protein meal (beef) compared to a moderate protein, high fiber meal (beans) on subjective appetite and energy intake at a subsequent meal. We hypothesized that a moderate protein, high fiber meal containing beans would be as satiating as a high protein meal containing beef. Twenty-eight adults, 14 men and 14 women participated in this randomized, controlled study in which subjects consumed two test lunches including a "meatloaf" made from either beef or beans. The primary outcome was to observe satiety ratings using visual analogue scales to assess hunger, satiety, fullness, and prospective food intake. Secondary outcomes included: food intake at the subsequent meal offered in the form of snacks, gastrointestinal tolerance, and palatability of the meals. No difference between the beef and bean was observed for appetite ratings over 3 hours, food intake at the subsequent meal, or sum of GI score. Gas and bloating were reported more often after the bean meal than the beef meal. The conclusion to this first study was that a beef-based meal with high protein and a bean-based meal with moderate protein and high fiber produced similar satiety, while the bean-based meal resulting in higher, yet moderate, gas and bloating.In the second study, we examined the effect of egg alone and in combination with whole grains compared to a refined ready-to-eat cereal on satiety and food intake in human subjects. We hypothesized that breakfast meals containing eggs, both high protein with white toast and moderate protein with whole grain toast containing fiber, would result in increased satiety ratings compared to an isocaloric standard refined cereal breakfast. Forty-eight adults, 24 men and 24 women, participated in this randomized, cross-over study. We designed whole food diets, controlled for macronutrients. The primary outcome was to observe satiety ratings using visual analogue scales to assess hunger, satiety, fullness, and prospective food intake. Secondary outcomes included: post-prandial blood glucose response, food intake at the subsequent meal offered in the form of an ad libitum pizza lunch, gastrointestinal tolerance, and palatability of the meals. No difference was observed between the cereal and egg + whole grain toast breakfasts for AUC for all satiety ratings however the egg + white bread breakfast was significantly improved for all 4 satiety ratings. Lunch intake was significantly reduced in both egg breakfasts compared to the cereal breakfast. No difference was observed for the sum GI score between the egg + white toast, egg + whole grain toast and cereal breakfasts, however gas and bloating was significantly higher for the egg + white toast breakfast compared to the cereal meal. Food intake at the subsequent meal was reduced for both egg breakfasts compared to the cereal breakfast. The results from these studies support the hypothesis that protein and fiber contained within whole foods results in greater satiety than refined carbohydrate foods. Protein, with and without fiber, produced the greatest satiety outcomes suggesting that the incorporation of high protein foods into the diet, specifically for breakfast, may result in greater feelings of satiety that could lead to decreased food intake and weight loss over time.Item Satiety, glycemic, and gastrointestinal effects of novel fibers(2012-06) Klosterbuer, Abby SusanEpidemiological studies have shown that dietary fiber consumption is inversely associated with body weight, and some research suggests that foods high in fiber increase satiety and reduce energy intake. The mechanism for this relationship is unknown, but may be related to changes in glucose, insulin, or gut hormone concentrations. Fiber may also benefit health by improving laxation, altering the gut microbiota, and increasing production of short chain fatty acids (SCFA). The following work describes two review articles, as well as an intervention study designed to help examine these effects. The first review focuses on the benefits of dietary fiber in clinical nutrition. This allowed for evaluation of the physiological effects of different types and combinations of fiber in subjects on a controlled diet. In general, blends of fibers with varying physicochemical properties provided greater benefits and were better tolerated than single fiber sources. Next, a systematic review of the effects of fiber intake on gut hormone concentrations examined the evidence for this relationship. Considerable variation was found in study design, population, fiber type and dose, which made comparisons difficult. Few studies reported a significant effect of fiber on gut hormone levels, and data suggest caloric load may have a more significant influence. Lastly, a randomized, double-blind, crossover study examined the effects of three novel fibers with varying physicochemical properties on satiety, stool characteristics, and the role of gut hormones, glucose, and insulin in appetite regulation. On Day 1 of the study, healthy men and women consumed either a low-fiber control breakfast or 1 of 4 iii breakfasts containing 25 g fiber from soluble corn fiber (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). Subjects rated satiety using visual analog scales (VAS), and blood samples were collected at various time points for 3 hours following breakfast. The fiber treatments did not influence satiety or energy intake compared to control. The RS+P treatment significantly reduced glucose, insulin, and GLP-1 concentrations. To examine the effects of chronic fiber intake, subjects consumed the fiber treatments at home for 6 additional days, with a 3 week washout between periods. Stool samples were collected on Day 7 and tolerance was assessed following fiber intake on Day 1 and Day 6. Fiber did not alter stool weight or stool consistency. SCF reduced pH and increased total SCFA production compared to control, while RS+P increased the percentage of butyrate. Overall, fiber was well tolerated, although treatments containing pullulan tended to cause minor increases in symptoms. Both SCF treatments resulted in a significant shift in the microbial community. Results from these studies confirm that different fibers vary in their physiological effects, and consuming fiber from a variety of sources may be most beneficial. Although increased satiety and improved bowel function are commonly reported benefits of fiber intake, it is clear that not all fibers exert these effects. In addition, the relationship between fiber and potential biomarkers of satiety remains unclear. Thus, it is important to evaluate the effects of different fibers in human studies to better guide recommendations for their use.